Auxiliary hot water heater



Sept. 6, 1949. D. w. MAIN AUXILIARY HOT WATER HEATER 2 Sheets-Sheet 1 Filed May 11, 1946 44444424441 424M44241144=M4M$ 1 .INVEN TOR. 54 W0 M/ MA m.

A TTOENEY.

Sept. 6, 1949. D. w. MAIN AUXILIARY HOT WATER HEATER 2 Sheets-Sheet 2 Filed May 11, 1346 INVENTOR.

84 W0 14/ MA/N.

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Patented Sept. 6, 1949 UNITED STATES- orrl-ce This invention relates to improvements in heat transfer devices and has reference more particularly to-an improved device for abstracting heat from flue gases.

It is well known that the heating systems commonly employed in residences and small apartment houses are very in'efiicient. Tests have shown that the heat loss in such systems is some times as high a 60% of the heat actually liberated bythe burning coal and that they seldom fall below 30%.

In the ordinary furnace employing coal, and to some extent when gas or oil is employed, the gases of combustion enter the smoke pipe at temperatures much higher than that required for'draft purposes and all heat is excess of this is wasted.

It is the object of this invention to produce an apparatus and a combination of elements by means of which a large amount of the heat that would otherwise pass to and up the chimney will be conserved and utilized.

It is obvious that any'device connected with the flue gas conduits for the purpose of abstracting heat from the flue gases lower the temperature and my invention contemplates the use of means for adjusting the abstraction to an amount that will not interfere with the draft.

A further object is to produce a heat exchange unit of such construetio'n that it can be readily installed in any heating plant.

Another object is to produce a heateiicha'nge unit or vent pipe that can be easily cleaned.

A still further object is to produce a heat exchange unit so that hot gases will contact large surface areas to facilitate heat transfer.

The above and such other objects as may 'appear 'as' the description proceeds are attained by means of a construction and relationship of parts that will now be described in-detail, and for this purpose reference will be had to: the accompanying drawings in which the invention has been illustrated, and inwhich:

Figure 1 is a view partly in elevation and partly in section showing my improved heater transfer unit in assembled relation;

Figure 2 is a transverse section taken on line 22, Figure 1;

Figure 3 is a longitudinal diametrical section taken on line 3 3, Figure 2;

Figure 4 is a section taken on line 4-43, Figure 2;

Figure 5 is a View similar to that shown in Figure 1 and shows a slightly modified construe tion; 7.

Figure 6 is a fragmentary detail showing one feature of the'construction 'of the combustion gas' flue;

Figure 7 is an assembly'view showing my invention embodied in a water heating system; and

Figure 8 is asection' similar to that shown in Figure 2, but shows a slightly modified form thereof;

Referring now to Figure "7, reference numeral I0 designates an 'ordihary'furna'ce of the hot air type having openings H for hot air hues. Referenc'e numeral l2' designates the furnace smoke' pipe which has been shown as provided with an elbow i3" arrd-which extends into chimney Positioned adjacent the furnace is a hot H. water tank 5 of any suitable type, preferably an automatic gas operated hot watertank. Reference-numeral l6 designates an auxiliary water tank and reference numeral I1 designates the heat transfer-unit to which this invention relates and which Will now be described in detail;

may be of the usual furnace pipe construction and ordinarily has a diameter of eight inches; althoughthe size and length is' immaterial so far'as this invention is concerned.

One section of pipe l2; the one shown in Figure 1, is'provid'ed'at itstop with an opening it; which is shown more clearly in Figure 6 to which reference-may be had. A damper i9 is positioned on the inside of the pipe and is, mounted for pivetalmovernent about hinged pin 2e. Means is provided for moving the damper and for hold ing-it in adjusted position's'oh'iewhat as shown in Figure 6. The adjusting means has been shown in'a general Way in Figure 7 of the drawing and maybe so constructed that the frictional resist-' ance-0r the hinge will hold the damper in ad= jus'ted. osition; however, any other suitable means in addition thereto maybe used, if desired. Supported on the upper surface of pipe 12 is a water chamber comprising an elongated hollow body" 2| that rests saddle-like against the upper surftt'ee ef tne pipe. In the embodiment shown, member at is senii=cyliiidrical and. the inner surface is folded'so as t6 produce longitudinal rihs 22 that extend upwardly to point 23, near the inner surface of the outer'wan. The inner Ver tic'es or the fiil'dedliiner wall, which have been designated'by reference numeral 2%, are some what'undulated as shown in Figure 4, so to rovide gaps 25 through which soot may escape and which facilitates el'eaning, in a mannerwhieh direction of arrow 44.

through opening 28.

will hereinafter be pointed out. Water is introduced to the lower end of member 2| through pipe 26 and leaves through pipe 21 which is connected in the outer wall thereof. Since the smoke Pipe is preferably upwardly and rearwardly inclined, water, when introduced through pipe 25;

will have to fiow upwardly to the exhaust pipe 21 when its temperature is raised, because the specific gravity of heatedwater, is less than that of a lower temperature. Pipe l2 is provided with an opening 28 in its lower surface directly underneath the upper end of member 2| as shown in.

Figure 3.

A housing comprising an upper semi-cylindri cal shell 29 is provided with outwardly extend! If a large amount of water is used and the V automatic heater I5 is also in operation, valve 42' is closed and valve 46 is open and therefore ing flanges 30 that are bolted to similar flanges on the lower section 3| forming a closed housing.

The two parts are heldin assembled relation by.

means of bolts 32, as shown in Figure 2. Parts" I 29 and 3| may be covered with heat insulating material as shown. Section 3| has'a downwardly rearwardly. and rearwardly inclined inner surface 33 that terminates in a downwardly eXtending tubular. part 34. A damper-35 serves to close the opening in part 34 and is provided with a handle 36 that is accessibleon the outside for opening and closing the same.

Referring now again to Figure 7, it will be seen that pipe '21. extends upwardly to water tank I6 and isin communication with the interior thereof.. From ,the, other end of tank It, a pipe .31

extends downwardly andconnects with the cold 4 water pipe 38 abovethe "automatic heater l5. f.

The cold water pipethat connects with the city water supply hasbeen' designated. by reference' numeral 39 and the hotiwater pipe from tank'l5' has been designated by reference numeral 40..

This extends to a sink or other fixture and the flow of liquid therefrom is controlled by means of a valve 4|. A pipe and valve 42 connect the lower end of pipe 3'! with the hot water pipe 40.

Normally valve 42 is closed, but may be opened under certain circumstances which will be re- 7 ferred to hereinafter.

Let us now assume that the parts are connected as shown in Figure '7 and that a brisk coal fire is burning in the furnace; Gases of combustion will .flow through the smoke pipe and into the chimney. Since damper I9 is partially open, as shown in Figures 5 and 6, a portion of the gases of combustion will pass up i wardly through opening IS in the direction of arrow 43, while the other portion will flow in the pass through opening|8 will flow through the passages betweenthe inner wall of member 2| Some of the gases that and the .outer'surface of the smoke pipe and other portions will flow around the outside of member 2| and will then pass downwardly about. v1

the outer surfaceand 'finally again enter the smoke pipe through opening 28, in the direction of arrow'45 in Figure 3. A portion of the heated 3 gases'will flow through the smoke pipe and will keep the wall thereof very hot. Somev of this heat will be transferred by conduction to the inner wall of member 2| and this will be abp sorbed by the water in member 2|. surface of 'the hollow body 2| will also be kept hot by the action of the heated gases that leave pipe-| 2 through opening l8 and enter it again The heat from the gases of combustion will thus be absorbed by the water and since this is connected with tank It ina The outer manner similar to that in which a furnace coil 7 is connectedwithan ordinary hot waterheater,

whenever valve 4| is opened, water will be drawn from the top of tank l5 and will be replaced by warmwaterfrom tank l6 and this, in turn, will be'replaced by'cold water entering through pipe 39. The water from tank It will be delivered to the interior of tank l5 through the downwardly extending cold water pipe 38 that terminates at 41 Y z- 7..

It will be seen. from the above that the auxili-* ary heater, that forms the subject ofthis invention, with its tank |6 forms an independent hot" water heating unitthat serves'as a preheater for water in tank l5. Lessheat is therefore required to heat the wateri'in' tank l5 tothe temperature desired; 5 E 1 Referring now to (Figure 8 where a slight modification has been shown, it willbe'seen that the upper half of pipe [2 has been removed,leaving T a hole or opening that is; closed lemme-elongated member 2|; =Since,..-there is, no wall between the inner longitudinal-ribbed wall of member '2.| and the inside of pipe; |2, thehat'ed gases are "free to come intodire'ct contact with'the, surfaces of.

the longitudinal grooves 48. This gives'a'zdirectl contact between. the hot-gases inside of the pipe and the inner surface of thewatercontain-ing element 2|. With the exception of the removal; i

of the upper Wall of pipe '-l2';the arrangement shown in Figure 8 is identicalwith that shown in Figures 1 to 3, inclusive, Q

In places where a somewhatisimpler and-Jess expensive, installation is'desired, ;memb eri2| may ,i be replaced by a coppertu-bel49, which is wrapped l I helically around-the furnace smokejipip'e as shown in Figure 5. The'waterzenterspat 26a and-leaves at 21a.- Theheated. gases{that-passthrough opening |8"come into direct fcontact with the outer surface of pipe 49- and transfers heat'to'the pipe and to the water contained therein.;--At-the same time heatgis conducted ffrom, theagas on the interior ofpipe|2 to pipe 29 and to the water therein. In order to'assure that nooonsiderable amount of air willrbeztrappedin pipes49, every turn of the pipe is'connected at. its highestpoint to a drainpipe 50 that connects with pipe 21 at. some suitable point betweentheheater andtank It, as shown in Figure 7.;

If, for any reason, the auxiliary heaterr that forms the subject of this invention becomes inop- 1 erative, it may be disconnected-by closin'g'valv'es El and 52. With these valve's'closed. the auxiliary heater, may be entirely removed, ifdesired. .Tank I5 will remain in the position showinj] The'e'nclos ing housing may, of'course, be:covered'withinsu-j V lating material 53, if desired, l The gases that leave a furnace are always quite hot, their temperaturedepending on vari ous considerations, forexample the heat ab stracting properties of the furnace itself, the directness of the path from the.combustion chamher and the velocitysofith gases oficombustion; .i After the gas leaves the furnace proper, an'yt?" heat that is contained in them is dissipated. The only useful portion thereof being that which is required to produce the necessary draft by hydrostatic action, due to differences in temperature and density. Since the gases are always much hotter than necessary to produce the required draft, all of the heat above that may be abstracted without in any way interfering with the operation of the heating plant and any heat thus abstracted costs nothing because it is not made use of, it is simply dissipated.

In the embodiment shown in Figure 5, in addition to damper 35, a removable cap 350. has been shown. This cap serves to more closely seal the outlet to prevent the entrance of air at this point.

Referring to Figure '7, attention is called to the handle 54 that is accessible from the outside and by means of which damper 19 may be adjusted whenever required to obtain the best division of the heated gases.

From time to time the auxiliary heater must be cleaned and this is accomplished by tapping the outside dislodging any soot that may adhere. The soot falls into the top surface of member 3| and flows downwardly lodging on damper 35 and may be removed by opening the damper.

By placing the heat absorbing member 2| on the outside of pipe 12, the draft is not interfered with and by means of damper is, the maximum quantity of heated gases may be bypassed and brought into contact with the outer surface of member 2|.

Referring now to Figure 3 which shows opening 28 in the under side of pipe l2. Attention is called to the fact that this opening may be elongated or enlarged to any extent and it will then allow fly ash to fall through and onto the upper surface 33 of the lower part. The fly ash may then be readily removed through pipe 34 by opening damper 35.

Referring again to Figure 4 and to the gap 25, attention is called to this feature of the construction. With gaps like the soot and fly ash that would otherwise collect in the spaces or channels above the outer surface of conduit l2, can escape and drop into the compartment below the conduit. By striking the wall of the outer housing or conduit [2, the ash may be loosened to facilitate its passage through openings 25,

Having described the claimed as new is:

1. In combination with a pipe having a section for the escape of hot gases of combustion, means invention, what is for abstracting heat from the gases, comprising,

a housing enclosing a portion of the section of the pipe, the latter having an opening in the top, communicating the interior thereof with the interior of the housing at the gas inlet end, and an opening in the bottom near the other end of the housing, whereby hot gases may enter the housing through the first mentioned opening and leave through the other opening, an elongated substantially semi-cylindrical hollow heat absorbing body resting on the upper surface of the pipe in the housing, and means for circulating water through said body.

2. In combination with a pipe having a slightly inclined section for the escape of hot gases of combustion, means for abstracting heat from the gases, comprising a housing enclosing a portion of said section of the pipe, the latter having an opening in the top communicating the interior thereof with the interior of the housing at the gas inlet end, and an opening in the bottom near the other end of the housing, whereby hot gases may enter the housing through the first mentioned opening and leave through the other opening, a hollow heat absorbing body in the housing, means for circulating water through said body, a damper in the first mentioned opening, and means accessible from the outside for controlling and adjusting the position of the damper to change the proportion of the gases passing through the housing.

3. In combination with a pipe having a slightly inclined section for the escape of hot gases of combustion, means for abstracting heat from the gases, comprising a housing enclosing a portion of said section of the pipe, the latter having an opening in the top communicating the interior thereof with the interior of the housing at the gas inlet end, and an opening in the bottom near the other end of the housing, whereby hot gases may enter the housing through the first mentioned opening and leave through the other opening, a hollow heat absorbing body having one side concave, positioned in close contact with the outer surface of the pipe, and means for circulating water through said body.

4. A device in accordance with claim 1 in which the bottom wall of the housing has an opening through which soot may be removed and means for closing the opening.

5. A device in accordance with claim 1 in which a damper is provided in the pipe adjacent the first opening for varying the proportionate amount of hot gases that pass tlTrough the housing.

6. In combination with a pipe for the escape of hot gases of combustion, means for abstracting heat from the gases, comprising a housing enclosing a section of the pipe, a hollow heat absorbing body positioned in the housing, the side of the body facing the pipe being curved to conform to the shape of the latter, the concave inner surface being longitudinally fluted, the vertices being longitudinally undulated to provide openings for the escape of soot and fly ash.

DAVID W. MAIN.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 687,735 Elmendorf Dec. 3, 1901 1,206,081 Becker et al Nov. 28, 1916 1,896,671 Heaps Feb. 7, 1933 2,020,686 Kaiser Nov. 12, 1935 2,035,341 Radloff Mar. 24, 1936 

